The direction
read-only property of the IDBCursor
interface is a string that returns the direction of traversal of the cursor (set using IDBObjectStore.openCursor
for example). See the Values section below for possible values.
A string indicating the direction in which the cursor is traversing the data. Possible values are:
next
-
This direction causes the cursor to be opened at the start of the source.
nextunique
-
This direction causes the cursor to be opened at the start of the source. For every key with duplicate values, only the first record is yielded.
prev
-
This direction causes the cursor to be opened at the end of the source.
prevunique
-
This direction causes the cursor to be opened at the end of the source. For every key with duplicate values, only the first record is yielded.
In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. Within each iteration we log the direction of the cursor, something like this:
prev
Note: we can't change the direction of travel of the cursor using the direction
property, as it is read-only. We specify the direction of travel using the 2nd argument of IDBObjectStore.openCursor
.
The cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo
. For a complete working example, see our IDBCursor example (View the example live).
function backwards() {
list.textContent = "";
const transaction = db.transaction(["rushAlbumList"], "readonly");
const objectStore = transaction.objectStore("rushAlbumList");
objectStore.openCursor(null, "prev").onsuccess = (event) => {
const cursor = event.target.result;
if (cursor) {
const listItem = document.createElement("li");
listItem.textContent = `${cursor.value.albumTitle}, ${cursor.value.year}`;
list.appendChild(listItem);
console.log(cursor.direction);
cursor.continue();
} else {
console.log("Entries displayed backwards.");
}
};
}